Wall covering material and method of making the same



Patented Nov. 211, 1935 warren sr WALL CUVERING MATERIAL AND IWE'KHQED OF MAKING THE Sm ltouis Carl Fleck, Appleton, Wis, assignor to Paper Patents Company, Neenah, Wis, a corporation of Wisconsin No Drawing. Application June 23, 1931 Serial No. 546,434

ll Claims.

My invention relates broadly to wall covering materials and has to do more particularly with an improved type of wall covering comprising a sheet of paper or the like having an applied coating, which is susceptible to a wide variety of artistic finishes, so as to be capable of simulating more expensive wall finishes. In its preferred form the base sheet is also subjected to an embossing process.

A particular object of my invention is to provide such a material, the surface of which will be highly water-proof and resistant to mild soaps and other cleansing materials, so that the same may repeatedly be washed without deterioration of the wall covering.

A further object is to provide a new and improved process ior producing an article of the class described, which process will be eflicient, economical, expeditious, and otherwise thoroughly satisfactory.

Various other objects and advantages will become readily apparent as the description proceeds.

For some time it has been recognized that it would be highly desirable to have a satisfactory washable, embossed wall paper. Flat papers had been successfully water-prooied, but such papers cannot be embossed after lacquering because the embossing process cracks the film, thus destroying the waterproofness at those places. Furthermore, with the previously known coating compositions, a paper could not be conveniently and cheaply coated after embossing because of the difiiculty of getting the composition into the recesses of the embossing with the usual processes of spraying or brushing.

After very extensive experimentation, I have evolved a process and coatingfizomposition which I believe to be new for producing an embossed water-proof paper at a very low cost and which avoids all of the difficulties just referred to.

Briefly considered, my improved process comprises first subjecting paper, which may be of any suitable type and grade of paper adaptable for the purpose, but is preferably what is known to the trade as No. 1 hanging stock, either decorated or undecorated, to an embossing process. This may be accomplished by any well-known or other suitable method. As this procedure is usually conducted, the decorated paper is run through what is commonly known to the trade as an embossing machine. This machine is quite common and well-known to all paper converters. It consists essentially of a top steelroller and a bottom fiber roller. The top steel roller has a design or pattern engraved or milled in its surface and the fiber, or bottom roller, has the reverse or oppo site of this same design on its surface. The two rollers are matched and might be called a male and female roller, so that the raised design on the top roller fits into or meshes with the depressed design on the bottom roller. An ink fountain and distributing roll can be attached to the top roller so that a thin film of ink can be applied to the raised portion on the top roller if desired, the result being that when paper is passed between these two rollers it is given the embossed effect with the same pattern that has been engraved on theserollers and the depressions in the paper may be inked or colored, which brings out the efiect of the embossing. No apparatus is shown in this connection, for the reason that such apparatus is well-known and I do not consider my invention as limited to any special form of equipment.

After the embossing step, the embossed paper is run through a coating machine and coated with a special coating material embodying my invention, dried on drying festoons, and then put up in rolls.

My improved coating material in its preferred embodiment comprises an ammoniacal emulsion of bleached shellac to which have been added other emulsifying, water-proofing and plasticising agents. I obtain the best results when the shellac is bleached by the following method:

I dissolve four pounds of sodium hydroxide in 500 pounds of water and heat the solution to 95 degrees C. with live steam. I add 100 pounds of shellac, gradually heat to boiling (95-l00 C.), and agitate with live steam. The shellac dissolves in about ten minutes. I then add 147Q pounds of cold soda bleach solution containing 1'7 gm. available chlorine per liter. I maintain the temperature in the tank at 70 C. until all bleach is added, then raise the temperature to 80 C. with live steam. When the chlorine is exhausted I cool the solution to 20 C. and then add 18 pounds of sulphuric acid (Sp. Gr. 1.83) dissolved in 100 pounds of water to precipitate the bleached shellac. I wash the bleached shellac with hot water (8090 C.) using two to three times as much water as volume of shellac foreach washing.

The following formula represents a preferred example of my improved coating material and method of preparing the same:-

Pounds .Stearic acid about 4 Japan wax about 5 Triphenyl phosphate about'8 Qibutyl phthalate aboutl The above materials are fiuxed in a steam jacketed aluminum kettle at about .90 degrees C.

. and to this flux is slowly added about 58 pounds of bleached shellac (containing about 40 per cent water) while stirring. The batch is then cooled to about 70 degrees C. About one quart of ammonia water (27 per cent), is then added with stirring. Then, with continued stirring are added alternately about three gallons water, three quarts more of ammonia water, three gallons water, three pounds rubber latex solution diluted with more water, and then further addition of water until the final volume is about twenty-eight gallons. The final temperature is about 60 degrees C. I sometimes grind a quantity of aluminum stearate in with the above formula to add additional dullness to the coating. This may be any desired quantity, but I prefer about 2 pounds. The

formula, as above described, is ready to put in the pan of the coating machine- The coating machine may be of any wellknown or other suitable type and hence no particular apparatus for this purpose is illustrated. In the usual coating machine which I may use, the paper from the reel first passes around a roller which is placed above a trough of the coating materials.

The mixture is transferred from a roller revolving in the trough of coating material to a revolving brush, and from this to the surface of the paper. The amount of coating is regulated by controlling the speed of the said revolving roll with respect to the speed of the paper. The paper with this film of coating material on it then passes across a table, where the coating is smoothed and brought into good contact with the paper by means of a series of brushes working with a reciprocating motion across its surface. After leaving the brushes the paper is festooned on sticks and carried by a chain conveyor through a drying room. Paper treated with the said coating material should be dried at 55 C. to 60 C. for 20 to 30 minutes.

'By means of my invention, I have found it possible to place the coating material into all the recesses of embossed paper at a very lowcost so as to obtain a completely waterproofed product.

When similar results are produced with lacquers, the cost is high. This is due to the fact that lacquer is viscous and requires much expensive solvent to thin it suiliciently to be brushed into the recesses of the embossing. To get sufficient water-proofing it may be necessary to apply two coats of thin lacquer or a large amount at one time. On the other hand, my invention uses water as thinner, and it is inexpensive, costing about one-tenth as much per roll as lacquer.

As to the functions of the various ingredients, the following theoretical considerations might be noted: Shellac is used as the base of the coating mixture, special bleached shellac being used because of its light color and greater solubility in the flux. The shellac is saponified, or partially saponified, in ammonia, so as to make it possible to obtain a water suspension of'this coating material. This is desirable for economic reasons, since a spirit suspension, so-called spirit varnish, such as is ordinarily used, would be entirely too expensive for my purpose. Ammonia is used for saponification of the shellac in place of some of the fixed bases because, when the paper is suiiiciently dried and the ammonia is driven off, the shellac remains behind in an insoluble form. Triphenylphosphate and dibutylphthalate are, of course, well-known plasticizing agents. Wall paper, of course, must be rolled, bent, creased, and hung. Hence, the coating must be highly plastic in order to avoid cracking the film, in which event penetration of water would be permitted. Latex may also be considered as a plasticizer, since it enhances the flexibility of my film. Latex is also believed to provide some degree of resistance to grease and oil and also a slight dulling of the film which is desirable for esthetic reasons. Japan wax is used to increase the water resistance of the film and it also assists in emulsifying the shellac. Stearic acid is used as an emulsifying agent in the presence of ammonia, and as a plasticizer and waterproofing agent.

While the formula set forth above represents my preferred embodiment, which was discovered after extensive experimentation to yield the optimum results, it is not in any sense to be considered as limiting the scope of my invention, since numerous changes in proportions, as well as in the substitution of equivalent ingredients, may be made in the formula and in the procedure without departing from the spirit of my invention, the scope of which is to be determined solely from the appended claims, these claims being given as broad an interpretation as is consistent with the state of the art.

Coverings made in accordance with my invention may, by control of the ink embossing step, cleverly simulate various types of more expensive wall treatments, such as stucco, adobe, or other plaster effects, leather, etc., etc.

I claim as my invention:

1. As a new article of manufacture especially adapted for use as a wall covering or the like, an embossed cellulosic sheet coated with a dry and highly flexible water-proof protective material, said material comprising a shellac base which has been emulsified with a relatively small quantity of rubber latex not substantially in excess of 4% of the quantity of shellac.

2. A method of producing an article of the class described, comprising embossing an uncoated felted cellulosic sheet and subsequently coating said sheet with an aqueous emulsion of a shellac, latex, and ammonia, the quantity of latex being a minor fractional proportion of the quantity of shellac, and then drying said sheet to produce a paper having a protective coating which is highly flexible while hard enough to resist abrasion and the like, said coating also being resistant to scrubbing with water and mild soaps.

3. As a new article of manufacture especially adapted for use as wall covering or the like,

a felted cellulosic sheet which has been embossed before being coated, said sheet having a dry, hard, and highly flexible waterproof protective coating comprising a shellac base, a quantity of rubber not substantially in excess of 4% of the quantity of shellac, and a plasticizer of the type of di-butyl phthalate, said coating being highly flexible while hard enough to resist abrasion and the like and resistant to scrubbing with water and mild soaps.

4. An article as defined in claim 3 wherein the coating material has been applied in an aqueous carrier.

5. A method of producing an article of the class described, comprising embossing an uncoated felted cellulosic sheet and subsequently coating said sheet with an aqueous emulsion of a natural resin containing a quantity of latex not substantially in excess of 4% of the quantity of resin, and

msasas also ammonia, a natural wax, a fatty acid, and a plasticizer of the type of dibutyl phthalate, and then drying said sheet, to produce a paper having a protecting coating which is highly flexible while hard enough to resist abrasion and the like, said coating being resistant to scrubbing with water and mil-d soaps.

6. A method of producing an article of the class described, comprising embossing an uncoated felted cellulosic sheet and subsequently coating said sheet with an aqueous emulsion of shellac containing a quantity of latex not substantially in excess of 4% of the quantity of shellac together with stearic acid, Japan wax, a plasticizer of the type of di-butyl phthalate, and ammonia, and then drying said sheet, to produce a paper having a protective coating which is highly flexible while hard enough to resist abrasion and the like, said coating being resistant to scrubbing with Water and mild soaps.

7. A method of producing an article of the class described, comprising embossing an uncoated felted cellulosic sheet and subsequently coating said sheet with an aqueous emulsion of shellac containing a quantity of latex not substantially in excess of 4% of the quantity of shellac together with stearic acid, Japan wax, a plasticizer of the type of di-butyl phthalate, ammonia, and aluminum stearate, and then drying said sheet, to produce a paper having a protective coating which is highly flexible while hard enough to resist abrasion and the like, said coating being resistant to scrubbing with water and mild soaps.

8. A method of producing a wall paper, comprising embossing a felted cellulosic sheet and subsequently coating said sheet with an aqueous emulsion of a natural resin and latex, the quantity of latex being a minor fractional proportion of the quantity of said resin, and then drying said sheet to produce a paper having a coating which is highly flexible while hard enough to resist abrasion and being resistant to scrubbing with water and mild soaps.

9. A wall covering material comprising a felted cellulosic base which has been embossed before being coated, said base having a protective coating of substantially translucent plastic material, comprising a resin with about 3%;% of rubber based on the quantity of resin, said coating being highly flexible and capable of resisting checking for a long period of time, being sufficiently hard to resist abrasion, and also being resistant to scrubbing with water and mild soaps.

10. A material as defined in claim 9, wherein the resin is shellac and the coating includes a plasticizer of the type-of di-butyl phthalate.

11. An article as defined in claim 1, wherein the quantity of rubber is approximately 3/::% of the quantity of shellac. LOUIS CARL FLECK. 

